Its actually a colloquial word which is the shortened version of "Jien m'hinix" meaning I am not... It is never used in written Maltese but very common in the spoken language, especially dialects. Side note on "M'hemmx" - means "there is not" only. To say there is nothing you have to add "xejn" afterwards.

Dear Abby ... Please correct any mistake

I was reading the Dear Abby letters the other day and <font style="background-color: yellow;">I</font> was amused <font style="background-color: rgb(0, 255, 0);">(amused is used when you were interested in a joking / matter of fact way. Intrigued is used in a more grave or serious scenario. Depends on the contents of the Dear Abby letter)</font> with the problem presented . And <font style="background-color: rgb(255, 255, 0);">I</font> was more <font style="background-color: rgb(255, 255, 0);">shocked</font> with the <font style="background-color: rgb(255, 255, 0);">response</font> she gave to the woman . The girl has a boyfriend but she wants to <font style="background-color: rgb(255, 0, 0);">live life up</font><font style="background-color: rgb(255, 0, 0);"> (I am not familiar with this expression)</font> as she said. <font style="background-color: rgb(255, 255, 0);">T</font>he Dear Abby told her to go and tell her boyfriend and<font style="background-color: rgb(255, 255, 0);">,</font> if he is like 99 % of the men in the planet he would be ok with her to go and be with <font style="background-color: rgb(255, 255, 0);">an</font>other. <font style="background-color: rgb(255, 255, 0);">It</font> is just weird for me. <font style="background-color: rgb(255, 255, 0);">It</font> may be a cultural thing but <font style="background-color: rgb(255, 255, 0);">I</font> don<font style="background-color: rgb(255, 255, 0);">'</font>t <font style="background-color: rgb(255, 255, 0);">believe</font> that there is a man who would be happy if his <font style="background-color: rgb(255, 255, 0);">girlfriend</font><font style="background-color: rgb(0, 255, 0);"> (lady is rarely used in this sense. Stick with girlfriend or wife</font>) <font style="background-color: rgb(255, 255, 0);">were</font> with other men.